One of the objectives of this research is to provide definitive data on the energy of electrons trapped in irradiated single crystals. The activation energy for detrapping will be determined from measurements on single crystals in which the arrangements of polar groups forming the trap is known from ENDOR studies. Another objective is to clarify the mechanisms involved in radiation-induced oxidation of the carbohydrate component of nucleic acids. V band ESR and ENDOR spectroscopy will be employed to examine the consequences of ionizing radiation on the backbone structure of dinucleotides. Studies of radiation effects in nucleic acid homopolymers will be carried out using 13C NMR spectroscopy. Damage to purine bases will be examined and 13C enriched polymer will be used in order to enhance the sensitivity of the 13C NMR analysis. Ionizing radiation will be used to generate certain metabolic intermediates artificially so that they can be characterized from ESR and ENDOR measurements.